ML20072A475

Forwards Response to Allegation That 55 Gallon Drum Was Left in Reactor Bldg Cubicle Roof & Response to Addl Info Requested by NRC on Masonry Wall Design Based Upon NRC Field Visit to LaSalle County Station During Wk of 820823

ML20072A475
Person / Time
Site:	LaSalle
Issue date:	09/30/1982
From:	Schroeder C COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20072A479	List: ML20072A475 ML20072A499
References
5136N, NUDOCS 8301240036
Download: ML20072A475 (3)

Text

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O-

'N Commonwealth Edison

) one First Nitiond Ptna. Chicago _, Ilknots

-v Address Reply to: Post Office Box 767 Chicago, Illinois 60690 September 30, 1982 Mr. James G. Keppler, Regional Administrator Directorate o f Inspection and Enforcement - Region III J U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137

Subject:

LaSalle County Station Units 1 and 2 Additional Information Regarding Allegations NRC Docket Nos. 50-373 and 50-374

Dear Mr. Keppler:

The purpose of this letter is to transmit to you the following documents:

1. LaSalle County Station, Commonwealth Edison Company, Response to Allegation That A 55 Gallon Drum Was Lef t In The Reactor Bulloing Cubicle Roo f G El. 723'6", dated 9-22-82.

2. Response to Additional Information Requested by NRC On Masonry Wall Design based Upon the NRC's Field Visit to LaSalle County Station Du ring the Week o f August 23, 1982, dated 9-23-82.

Both of these reports were developed for the sole purpose of responding to requests from your staf f in their ongoing investigation of allega-tions.

If there are any further questions in these matters, please contact this of fice.

Very truly yours, OsA k , Min C. W. Schroeder Nuclea r Licensing Administrator 1m cc: Mr. A. Schwencer 1/1 NRC Resident Inspector - LSCS 1/0 OCT 4 082:

5136N C301240036 820930 PDR ADOCK 05000373 A PDR _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

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LASALLE COUNTY _ STATION COMMONWEALTH EDISON COMPANY RESPONSE TO ALLECATION THAT A 55 GALLON DRUM WAS LEFT IN THE REACTOR BUILDING CUBICAL ROOF @EL. 723'-6" This cubical is situated in the Reactor Building, above floor elevation 710'-6, between column lines 16-17.2 & G-6.6' west of H.

The cubical contains a vertical heat exchanger with drain water entering and leaving at the top.

This slab is 36" tnick with #6 horizontal bars at 12" centers in both directions at top and bottom. Assessment of the slab thickness has been made considering a 55 gallon drum (24 inch diameter and 36 inches long) situated at any location in the roof slab. The assessment has been made for stress and radiation requirements considering a 24" dia x 36" long void.

Engineering Assessment The roof slab has been assessed for a span of 15'-8 using ultimate strength design method, proper load factors and load combinations.

In flexure, the slab has a safety margin of 2.0 (actual moment =

33.76 ft. kips, moment capacity = 67.9 ft. kips). For shear, considering the drum was located near the support; the slab has a safety margin of 2.2 (actual shear stress = 57 psi, allowable shear stress = 126 psi).

Radiation Requirement Assessment The 36" thick roof slab has been provided based on the original -

shielding design for a larger collection tank. Presently the actual equipment and piping in this room are:

a. One heat exchanger with primary coolant on the tube side and service water on the shell side.

b. The radiation source is 100% reactor water decayed for 90 seconds. The piping was assumed to'be 2" schedule 40 pipe.

The analysis indicates that considering 12" of concrete being effective, the actual dose rate above the roof will be less than 4 mr/hr. This is less than the permissible (design dose rate for the roof) dose rate of 5.0 mr/hr., therefore no special health-physics i procedures will be required.

The 36" roof slab of the cubical at El. 723'-0 is capable of carrying the design loads and meets the radiation shielding requirements even if 24" dia x 36" long 55 gallon drum is located in the most critical

! position in the slab.

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